Rpqueue

[fixed] on some runtime virtualization platforms, /dev/shm is not available.
We work-around this by not using multiprocessing on those platforms, and
reducing processes to 1.

[added] Dockerfile and docker-compose examples for testing every supported
version of Python + rpqueue we support.
[removed] References to Python 2.6 and 3.3 in supported versions (2.6 has no
available container, 3.3 has weird protocol issues in Redis)
[fixed] Supported versions of Python references in setup.py .
[fixed] issue with loading some data in Python 3.4 and 3.5 (not present in
other versions)
[fixed] doc generation is now inside a container, so no more local system
pollution

[added] sponsorship docs

[fixed] fixed crontab queue definitions, again :/

[fixed] fixed crontab queue definitions

[added] log messages for scheduled tasks if/when they are created, to help with
bad periodic delays or cron task delays. Requested by github user
https://github.com/tinkerer
[added] rpqueue.flush_tasks() to finish outstanding tasks in the queue, intended
primarily to start tasks when you need them all to finish (testing, prod
resources going away, etc.)